1. Field of the Invention
The present invention relates to a method for manufacturing a laminated iron core (a rotor-laminated iron core or a stator-laminated iron core) having multiple punched holes (for example, magnet-insert holes) in its circumferential direction, using a motor.
2. Description of the Related Art
Recently, as disclosed in JP-A-2008-42967, there has been spread a motor using a rotor structured such that its rotor-laminated iron core having an axial hole in its center includes multiple magnet-insert holes in which corresponding permanent magnets are inserted and respectively resin-sealed.
However, when closed magnet-insert holes are formed in the rotor-laminated iron core, magnetic flux directed toward the front and back of the permanent magnets provides a magnetic path in the outer peripheral portions of the magnet-insert holes, thereby reducing the magnetic efficiency of the rotor. Thus, as shown in FIGS. 4A and 4B, there is proposed a method in which a bridge portion 71 formed between the end and outer periphery of a magnet-insert hole 70 of an iron core piece 72 forming a rotor-laminated iron core is plastically deformed by pressing to make the thickness of the plastic-deformed portion thinner than those of the remaining portions, thereby preventing an increase in torque variation, reducing the leakage magnetic flux and thus improving the efficiency of the motor (see JP-A-2006-50821 and JP-A-2012-16090). FIG. 4A shows a permanent magnet 70a and an axial hole 73.    Patent Literature 1: JP-A-2008-42967    Patent Literature 2: JP-A-2006-50821    Patent Literature 3: JP-A-2012-16090